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Title: In-situ crystallization of GeTe\GaSb phase change memory stacked films

Single and double layer phase change memory structures based on GeTe and GaSb thin films were deposited by pulsed laser deposition (PLD). Their crystallization behavior was studied using in-situ synchrotron techniques. Electrical resistance vs. temperature investigations, using the four points probe method, showed transition temperatures of 138 °C and 198 °C for GeTe and GaSb single films, respectively. It was found that after GeTe crystallization in the stacked films, Ga atoms from the GaSb layer diffused in the vacancies of the GeTe crystalline structure. Therefore, the crystallization temperature of the Sb-rich GaSb layer is decreased by more than 30 °C. Furthermore, at 210 °C, the antimony excess from GaSb films crystallizes as a secondary phase. At higher annealing temperatures, the crystalline Sb phase increased on the expense of GaSb crystalline phase which was reduced. Extended X-ray absorption fine structure (EXAFS) measurements at the Ga and Ge K-edges revealed changes in their local atomic environments as a function of the annealing temperature. Simulations unveil a tetrahedral configuration in the amorphous state and octahedral configuration in the crystalline state for Ge atoms, while Ga is four-fold coordinated in both as-deposited and annealed samples.
Authors:
 [1] ;  [2] ; ;  [1] ;  [3] ; ;  [4] ;  [1] ;  [5]
  1. Paul Scherrer Institute, CH-5232 Villigen-PSI (Switzerland)
  2. (Romania)
  3. National Institute for Laser, Plasma and Radiation Physics, RO-077125 Magurele, Ilfov (Romania)
  4. National Institute of Materials Physics, RO-077125 Magurele, Ilfov (Romania)
  5. (Switzerland)
Publication Date:
OSTI Identifier:
22402821
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; ANNEALING; ATOMS; CRYSTALLIZATION; ELECTRIC CONDUCTIVITY; ENERGY BEAM DEPOSITION; FINE STRUCTURE; GALLIUM ANTIMONIDES; GERMANIUM TELLURIDES; LASER RADIATION; PULSED IRRADIATION; TEMPERATURE RANGE 0400-1000 K; THIN FILMS; TRANSITION TEMPERATURE; VACANCIES; X-RAY SPECTROSCOPY